(b) sarcomere

Explanation:

Sarcomere is the smallest contractile unit of striated muscle fibre. Sarcomere occurs as repeating units along the length of a myofibril, occupying the region between Z lines of the myofibril.

Sarcoplasm is the cytoplasm of a muscle fibre. It is a water solution containing ATP and phosphogens, as well as the enzymes of intermediate and product molecules involved in many metabolic reactions. Neuromeres is a metameric segment of CNS. Metamere is a linear series of primitively similar segments into which the body of higher invertebrate and vertebrate is divisible.